In order to facilitate so called "mechanical" harvesting of grapes, many vineyards are now provided with rows of posts, each post having upwardly and outwardly sloping iron trellis arms pivoted thereto, and supported by an upwardly and inwardly sloping wires, the arrangement being such that the trellis wires are carried on the ends of the trellis arms, and the vines supported by the trellis wires can be vigourously shaken by a mechanical shaker so as to remove bunches of ripe grapes from the vines.
However, heretofore pruning has usually been a manual or semi-manual operation wherein an operator has separately severed each cane, arranged the remaining canes in such a way that they normally lie on and are thereby supported by the trellis wires, but it has been noted that such removal of the canes normally is effected by cutting all or nearly all of the canes which project outwardly from the trellis wires.
Attempts have been made heretofore to mechanise pruning, and reference is made to U.S. Pat. No. 2,940,486 (Whitmore) wherein a vertical row of saws is associated with a horizontal row of saws, but a device such as described and illustrated therein would be unsuitable for pruning vineyards owing to absence of a frame which can be swivelled to accommodate variations in height of the trellis, cross-bar, or inclination of the ground.
The U.S. Pat. No. 4,067,178 (Miller) discloses a device having a swivel arm arrangement for supporting saws, but such a device is also unsuitable for pruning canes from vines because of its inability to cut inside, top and outside canes simultaneously.